Method of and coupling for pressure pipes



Patented Aug. 2, less A I 1,125,324

UNITED, STATES PATENTfOFFlCE mrrnon OF AND COUPLING Poa PRES- scar: PIPES Karl D. Williams and Hugo W. Hicmke, Washington, D. 0.

Application April 1, 1935, Serial No. 14,168 7 Claims. (01. 29-1482) (Granted under the actsof March 3, 1883, as amended April 30, 1928;. 3'70 0. G. 757) This invention relates to an improved method pipe coupled thereto in accordance with our inof and coupling for pressure ferrous pipes, and vention; has for an object to provide a very efficient, sim- Fig. 5 is a plan view of a tool for flaring the ends ple, inexpensive and durable coupling for such of pipe to be joined in accordance with our in- 5 pipes which will not vary at the joint the area of vention; and

the bore of the pipe and enable the pressure Fig. 6 is a longitudinal view through portions medium to flow through the joint withthe same of pipes joined together with solder in accordance velocity and freedom from eddy currents inherwith our invention. ent in the flow through the bore of the pipe. Our new and improved method of coupling 10 Such freedom from eddy currents and varied pressure pipes will, for brevity and clearness, be 10 velocity in flow through the joint is highly addescribed in connection with the general descripvantageous, especially for fluids under pressure. tion of our invention. Furthermore, in couplings of such pipe where The ends of ferrous pipe It! to be joined are recesses are formed within the bore, in addition provided with an outward symmetrical flare H to the foregoing disadvantages, accumulations of of uniform taper and in which the metal of the 15 sediment are formed which are disadvantageous pip is pr siv ly t d s the a pfor many reasons, as well as tend in some cases to proaches the end of the pipe, as more clearly augment such eddy currents or otherwise impede shown in Fig. 2. This is most economically and the flow. conveniently done on the job or in the shop by Further objects of this invention are to proinserting into the bore of the end of the pipe in 20 vide a coupling for ferrous pipe which will not to be joined the pilot l2 of a tool l3 having hantend to weaken, but rather strengthen, the pipe die It provided with a preferably rounded outer at the coupling; to avoid weakening the pipe as end l5 and joined to pilot I! by an integral body well as coupling by screw threads; to join the It having a conical exterior conforming to the A pipes, and/or fittings without screw threads and taper of the flared portion ll of the pipe to be 5 by welding, brazing or soldering; and to form the joined, the'smallest diameter of said conical surcoupling substantially smooth and of uniform face being substantially that of pilot l2 and its continuous bore with that of the pipe and smooth largest diameter terminating in most instances in exterior contour of progressively increasing dia shoulder I! at the point of juncture with hanameter as the joint is approached. die 14. The pilot l2 of tool i3 is inserted into 3 I the lengths in which the same may be required to- Other objects of the invention will appear. to the bore of each end of ferrous pipes to be joined those skilled in the art from the following specitogether in accordance with our invention. The fication and claims. conical body portion it of tool i3 is then driven Heretofore, the teaching in the art of pipe or pressed into the pipe by pressure or blows upon 35 coupling for pressure fluid flow therethrough has the end l5 until the outer edge of the same regis- 35 been that ferrous pipe may not be flared at th ters with either lines l8 or I9 formed upon the d after th a h b n d of uniform outer surface of conical body portion IB near the diameter, t we have fou d t t t same may largest diameter thereof. This results in outward be conveniently done with such pipe cut to any of flaring of the end of the ferrous plpe to be Jomedi Into the flaring ends H of the ferrous pipe to be joined in accordance with our invention is inzggg y f of great Strength may be made serted a pipe thimble 20 having a bore 2| ex- 4 In the drawing Fig. 1 is a longitudinal cross- $3325 gi g ggi g g; l gg gigz fi ibfi fii gg 33 2 3 ?fi gg z ig g ggEff; P the Integral The thimble 20 is forr'ned of a continuous integral unseparated and unperforated body of metal f is gg g i wewfof surrounding its bore 2 i, formed thickest at sub- 6 en 0 i P omfed stantially the center of its length and tapering 5O coupling accordance W1 F f fl therefrom to opposite ends, with the largest 3 15 central longltudmal k diameter substantially in the center of the length throu h portion of theends oftwe e us p p of thimble 20, and its smallest diameter at its coupled accordarfcefvlth our mventlqn; opposite ends where a relatively thin edgeZZ is Fig, 4 is a longitudinal sectional view taken formed which merges into the bore of the pipe I0 through a portion of a fixture and a portion of a to be Joined together without disturbing the con- 55 be ,cut, and that a very simple, inexpensive and as heretofore described.

tinuity of the uniform diameters of the pipe l and of the thimble 20.

This merger of the bores of ferrous pipe l0 and ithimble' 20' into each other without disturbing the continuity of such bores of equal diameter affords uniform velocity of flow of the found that such turbulence and eddy currents in the flow of mediums under pressure in pipes occasions an electrolytic action upon the pipe and joint which induces or accelerates corrosion. While the sharp edges .22 at the opposite ends of each thimble 20 are liable to distortion or other damage in handling preparatory to use, and are objectionable for those reasons, it has been found that the same is advantageous when it is considered that the same avoids turbulence and/or eddy currents in the flow of pressure medium through the bore of the pipe and thimble 20, as well as avoids resulting electrolytic action and corrosion induced and/or excited thereby. The gradual tapers of the opposite ends of thimble 20 inward from its opposite thinned edges 22 furthermore enables the ends of pipe H! to be joined to be outwardly flared as at il-with progressively continuing tapers corresponding to their respeetive tapered ends of thimbleZG and which tapers progressively and symmetrically merge, at a substantial uniform rate, into the bore of pipe ID, as well as that of thimble 20.

At substantially the center of its length each thimble 20 is provided with an annular integral external bead or series of projections 23 against whose opposite edges the inner edges of the flared ends ll of pipes ill engage. as well as the degree of juxtaposition of the tapered'bores of thefiaring ends ll of pipes Ill and the tapered outer surfaces of their thimble 20, is controlled by the indicia l8, l9 upon' conical body N5 of the expanding tool l3. When a close fit between said tapering surfaces: is desired, the tool I3 is forced or driven into the ends of pipe to be joined until the inner edge of the flared end H of pipe l0 registers with the line or indicating means l8, which is positioned on the conical portion ofthe tool l3 so as to obtain the contact of the whole inner surface of flaring end ll of pipe ill with the whole tapered exterior surface of, and the base of bead 23 on, thimble 26. This closeor tight fit between said juxtaposedsurfaces is found most advantageous in the instances we have so far encountered in practice of our invention where the flared ends ll of pipe l0 are welded or brazed together.-

Such welding or brazing is indicated in Fig. 3, in which 24 indicates the welding or brazing fillet which surrounds the head or projections 23 and extends between the juxteposedends of the flared portions. ll of .pipe III joined together by our invention. In'such welding or brazing more or less of the juxtaposed, as well as contacting, surfaces are joined together firmly with high efficiency to resist stresses and vibrations i a in pipe installation in static structures, as well as the substantially greater vibrational stresses arising in pipe installation in dynamic structures such as automobiles, vessels, and especially naval J vessels.

Fig. 4 illustrates the same parts and practice as in Fig. '3, except that one of the pipes Ill of This engagement,

25 .is substituted therefor, whose pipe joint end 2615 provided by machining or otherwise with an inner tapering bore '21 corresponding to the. tapered end of thimble 20, which tapers progressively and symmetrically merge with the bore 28 ofvalve or fixture 25-, as well as the bore 2| of thimble 20. At this point of merger no tur bulence or eddy currents in the fiow of the pressure medium is excited or induced for the reasons and objects stated in connection with the disciosure of Fig. 3. Otherwise, the disclosure of Fig. 4 is the same as that of Fig. 3.

Thus far in the disclosure of our invention the same has been described as being adapted more especially to the concept of our invention when the joint is to be secured by welding or braking.

Fig. 6 discloses the structural adaptation to the concept of our invention of the solder securement of the joint. While it discloses merely the joining together of pipe, similar to Fig; 3, it will be understood, by those skilled in the art, that it may without modification be employed to secure a pipe end to a valve or other fitting, substan tially as indicated in 4. Otherwise than herein described, the parts shown in Fig. 6 are the same in structure and in function as those partsdisclosed in Figs. 3 and 4.

The thimble 20a, Fig. 6,'has all the structural and functional features of the thimble 23 heretofore described, and in-addition thereto the oppositely tapered perlpherical surfaces thereof are provided each with an annular recess 30. In flaring the ends H of pipe I to be joined in accordance with Fig.6, the tool 13 is driven or forced therein until the inner edge of the" flaring end of the pipe registers with the indication IS on tool 13. --This;insures a slightly greater end terminai diameter in the taper of the flaring end ll of pipe l0 over that of the corresponding end of the thimble 20a, so that when the inner edge of the flaring end ll of pipe HI contacts with the base of the bead 23 there exists between such juxtaposed tapered surfaces a relatively thin annular space such as has been found to produce and/or invite capillary attraction substantially facilitating the flow of molten solder in and about the joint, filling the capillary attraction space and the annular recess 30. and firmly and efiiciently uniting the ends of pipe and/or fittings to fittings, and/or pipe to fittings so durably as to resist stresses and vibrations such that joint failures have been occasioned even in threaded couplings.

It will furthermore be appreciated, especially by those skilled in the art, that joints made in accordance with our invention are substantially stronger than the normal strength of the pipe or ends of fittings joined together. This is due to a number of causes which we have so far ascertained, including, the increased strength afforded the flared pipe end by the cold working thereof, as well asby the increased diameter thereof, also by the relativeiy long thlmbles 20, 20a, reinforcing the strength of the flaring ends of the pipe throughout the whole extent of such flaring ends, so that the inherent 'rigiditypf the continuous, integral, unseparated and unperforated thimbles have a substantial length of bearing upon each of the flaring ends of'the pipe and substantially resist lateral and other vibrational stresses, as well as all other stresses at' the point of the juxtaposed ends of the pipe and distributing all such s'tresses'through thelength of each thimble.

and about the fillet metrical exterior surface gradually approaching its largest diameter at a point between the pipe ends, which diameter is no more than, if as much as, that of a wiped joint between the ends of lead pipe..

In connection with Fig. 6 each thimble 20a may be coated with solder and the annular recess 30 filled therewith, either in the factory or in the field, preparatory to making the joint. In this case after cleaning, and/or coating with solder, of the flaring ends and inner flaring surfaces of the pipe ends H in accordance with soldering practice, the thimble 20a. may be inserted into the flaring bores of pipe ends II and there held while heat is applied to said flaring ends II, and, consequently, to the thimble 20a, until the solder becomes molten, when additional solder may be placed between the pipe ends II or series of projections 23, whereupon the union may be permitted to cool. In cooling it will be observed that in the structures in each of Figs. 3, 4 and 6, the thinnest point of the joined pipe within the joined area is at thimble ends 22, 22a. through the wall of pipe l0, and that the thickest part of such joint is from the bore of thimble 20, 20a in the region of the head or projections 23, 23a. The functional advantage of said difference in thickness is furthermore attained by our invention, as

follows:

In the disclosure of Fig. 6 the solder joint will first cool to the point of non-fluidity substantially at the thinnest points of said joint, which is substantially at the opposite ends 22a of thimble 20a. This, with said capillary attraction space, as well as said annular recess 30, will insure a continuous body of solder without voids therein extending continuously between said ends 22a as well as between the flaring ends. ofjthe pipe l0.

Instead of the pre-coating of thimble 20a, Fig. 6, with solder, the same with the ends ll of pipe Ill may be prepared for solder in the usual way and assembled, after which they may be heated and solder applied between the juxtaposed ends of the pipe and about the fillet 23a. until a firm solder union is obtained thereby, in the manner heretofore stated' I, i

Said advantages relative to the disclosure of Fig. 3 are somewhat different, due to the different characteristics of welding or brazing, including the higher heat required. This higher heat stores a greater number of heat units in the thicker metal in the region of the bead 23', and progressively less heat units as the metal of the flaring end H of pipe l and of the tapered end of thimble progressively becomes thinner. Since the area of exchange of this heat to the surrounding atmosphere remains fairly constant, it will be appreciated that less of the welding heat will be at the thinnest point 22 where the same is farthest from the welding fillet 2 4, with the heat thereof progressively lessening as said point 22 is approached, and that the heat at point 22 will not only be lower but will cool substantially quicker than the welding fillet 24. This affords progressively less and less heat deterioration of the cold working characteristics of the flaring end ll of pipe l0 as the diameter of said flare decreases. This progressive condition has been found of substantial advantage in joints of all of the metals whose desirable characteristics may be enhanced by cold working; The same has also been found to be desirable and advantageous in the joining of pipes of steel alloys having a carbon content of higher than substantially .08. These alloys are numerousand include austenitic stainless steel, wherein the carbon, when afforded time ties requisite therefor, tend to migrate to the grain boundaries, carrying other constituents therewith. Said migration produces nonhomogeneity in the metal, occasioning undesirable conditions sometimes called carbide precipitation, also lowering the normal corrosion resistance of the alloy, as well as tending to brittleness where the carbon content is high. The quicker cooling of the welding or brazing heat at 22 insures, with its distance from the welding fillet 24, and the intermediate temperature drop,

that any undesirable degree of migration or carand temperature facili-- bide precipitation that may be occasioned will be well within the flaring length of the end H of pipe l0 which is strengthened, covered and protected from the through flowin'gprcssure fluid by the thimble 20. Thereby any such resulting disadvantageous condition does not practically affect the function, durability or resistance of the joint made in accordance with our invention in all the many conditions which we have encountered in practice.

It will be appreciated from the foregoing that the acts requisite to the practice of our improved method comprise the flaring of the ends of pipe and/or connections to a progressive continuous taper with the walls thereof of progressively thinner outer wall as the end is approached; inserting in the flaring ends to be joined a correspondingly oppositely tapered thimble having a bore therethrough corresponding to the bore of the pipe and/or connections to be joined together, and securing the partstogether by welding or soldering; and that other acts incident thereto may be readily understood by those skilled in the art from the foregoing speciflcation including those involving the heat transfer and the avoidance of turbulence, eddy currents, and the advantages obtained thereby.

We have also found that the pipe ends may as advantageously be flared in the shop where power is available by a roller expanding tool which has no expanding rollers in the pilot portion of the tool, but only in the conical portion of the tool.

The invention described herein may be manufactured and used by or. for the Government of the United States of America for governmental. .purposes without the payment ofroyalties thereon. or therefor.

Having now so fully described our invention that others skilled in the art may therefrom make ward at least one unheated end of the normally uniform bore of a ferrous pipe with a uniformly progressing taper and thinness of wall from its bore to its outer end, inserting in each flared end' the correspondingly flared end of a member whose bore conforms'to and uninterruptedly joins that of the pipes, securing the pipe and member with solder by flaring sufficiently the juxtaposed surfaces of said flared portions to form a capillary attraction space therebetween, and by cooling the solder heat below fluidity first near the smallest diameters of said juxtaposed flared surfaces.

2. In a coupling for ferrous pipe the combination of a pair of ferrous pipes whose adjacent ends are outwardly cold-flared with a. relatively ble of integral,

long slow taper or definite length progressing symmetrically from the bore of the pipe outward,

the metal of the flared portions of each pipe being as the taper extends out- I thinner progressively ward from the normal body of the pipe; a thimcontinuous and unperforated metal having a bore extending longitudinally 'therethrough conforming to, and merging unin- 4; The structure of claim 2 further character ized by the means comprising a. welding deposit securing together the flared ends of the pipe and by the length and progressive thinness of each of the taperedportions being such that the welding heat may not harmiully change the characteristics of the pipe except in an intermediate portion of the extent of the tapered portions.

5. In a pipe'coupling the combination of a pair of ferrous metallic pipes whose adjacent ends are outwardly flared with a relatively long taper of definite length, progressing symmetrically from the bore of the pipe outward, the metal of the flared portions of each pipe being thinner progressively as the taper extends outward from thimble having at the normal body of the pipe; a thimble of integral, continuous, and unperforated metal hav-. ing a bore extending longitudinally therethrough and conforming to, and merging at, each end uninterruptedly into, the bore of the pipe, said opposite ends a tapered exterior conforming inlength' and degree of taper to the interior tapered surface of the flaring ends of the pipe to be occupied thereby with a relatively thin substantially capillary attraction space extending between and at least throughout a. substantial extent of the juxtaposed tapered surfaces of the pipe and thimble, there being aspace between the adiacent ends of the pipe so occupied by said thimble, and said thimble being provided in said last named space with an outward projection against whose opposite surfaces the juxtaposed ends or the pipe are adapted to contact to maintain said capillary attraction spaces,

. whereby the pipe may be secured to the thimble 1 by solder occupying, said capillary attraction spaces. l

6. The structure of claim 5 further charac= terized by a space extending at least about asubstantial annular portion of each tapered portion of the thimble. v

7. The structure of claim 2 further characterized by the wall of the coupling at opposite ends of the thimble being thinnest whereby the solder may first cool to non-fluidity substantially at said 3 opposite ends of the thimble.

KARL D. s. 

